Re: Pruning Floppyheads

Tue Oct 03, 2017 5:55 pm

Hello, Carol. The shrub is getting too large? Well, that can be a nice problem to have sometimes!!! Hee hee hee. Just kidding! Sounds like it is happy with the way you take care of it! You did not say what variety you have but I hope the following helps...

Normally, the answer is to prune after the shrub has bloomed (so you get to enjoy the blooms for a little while) but before mid-to-late July (end of June for me in the South). You can either give all the stems a cut down to about the same height (how much depends on how vigorous the shrub is) or you can prune in thirds during the next three years (prune the longest stems in year 1, the next longest stems in year 2 and the rest in year 3). One thing that I sometimes do in the Fall is take advantage of the leaves that dry out: this allows me to see how the stems intertwine. I may then do selective pruning of stems that cross or prune stems where I want to force more sunlight. But I am talking about cutting off just a handful of stems with this Fall selective pruning. In the majority of years, my macros do not get large and their locations allows for large sizes anyhow so, I hardly ever prune (maybe once every 5 to 10 years)?

But I would also say the answer may depend on whether you winter protect or not. By that I mean… if you put something like chicken wire around the shrub during winter and pile it with dead leaves or mulch? That allows the invisible stems that developed already to survive your winter and produce an early Spring flush.

If you winter protect, I would NOT prune now because that would cut off the early Spring blooms. I would prune after blooming but before the end of July-ish.

If you do not winter protect or care about the early Spring blooms then yes, you could prune now.

In Zone 5, I would expect that an unprotected hydrangea in winter would typically "loose" all the stems due to cold drying winds & temps. But then, it would grow new stems from the crown when Spring arrives. In that case, you could leave it unprotected, let Mother Nature take care of "pruning for you during winter". Stems that do not leaf out by late May can be pruned all the way down. All you need to do in Spring is wait for new growth to hopefully come back from the crown. If you do this, a non-rebloomer macro would skip blooms in 2018 but a rebloomer is supposed to produce a late flush in the summer or thereabouts.

If you plan to prune all the stems down to the ground, I would do it once it goes dormant so it does not try to put energy in growing new stems in the Fall. I would also make sure that you have 3-4" of mulch up to the drip line now. I would cover/protect the crown with mulch now and remove the crown's mulch when the worst of winter has left for good in Spring. I normally do not cover the crown but your winters are too cold and I like to baby these shrubs too much. All I am trying to do is to protect all the roots from temps in your winters.

If pruning is something you end up doing too often, consider transplanting the shrub to a location where it can attain its large size without you having to prune every year. Then place a new but more compact hydrangea in that spot.